1. Field of the Invention
The present invention relates to a broadcast reception apparatus, and more particularly to a broadcast reception apparatus capable of receiving broadcast by using a directional antenna.
2. Description of the Background Art
Various techniques to cause a broadcast reception apparatus connected to an antenna for receiving airwave to carry out power ON/OFF control of the antenna have conventionally been disclosed. Such techniques are mainly directed to suppression of power consumption.
For example, Japanese Patent Laying-Open No. 2003-283351 discloses a technique to start power feed to a converter of a reception antenna on condition that at least one receiver is turned on in an apparatus connected to a reception antenna and a plurality of receivers and distributing airwave received at the reception antenna to the plurality of receivers.
In addition, Japanese Patent Laying-Open No. 2003-284063 discloses a technique to supply power to a reception antenna on condition that it is determined that no satellite broadcast wave is supplied when a satellite broadcast receiver is turned on.
Moreover, Japanese Patent Laying-Open No. 2004-221732 describes a technique related to a television broadcast reception apparatus including a terrestrial digital broadcast adapter, a satellite digital broadcast antenna and a digital unit used for receiving terrestrial digital broadcasting and satellite digital broadcasting. This publication discloses a technique to turn on one of the terrestrial digital broadcast adapter and the satellite digital broadcast antenna, depending on which is selected for broadcast reception.
Recently, a directional antenna capable of switching a radio wave reception direction has been invented as an antenna for receiving radio waves transmitted from towers of a plurality of distributed broadcast stations, instead of an antenna capable of receiving solely radio wave from one direction.
When such a directional antenna is connected, the broadcast reception apparatus not only should supply power to a variable directivity antenna but also should control directivity switching. An example of such a broadcast reception apparatus and a variable directivity antenna will specifically be described with reference to FIG. 3.
FIG. 3 shows a receiver 901 including a tuner complying with EIA Electronic Industries Association) 909 standard and an antenna 903 serving as an outdoor antenna of automatic directivity control type complying with the standard above and connected to receiver 901 through an antenna controller 902, as examples of a broadcast reception apparatus and a variable directivity antenna connected thereto, respectively. When an operation to switch a reception channel is performed in receiver 901, for example, by operating a remote controller or the like, receiver 901 adjusts directivity characteristic of antenna 903 to an electrically optimal reception direction.
Receiver 901 includes a modular terminal 913, a tuner 914, a decoder 915, and an OSD (On Screen Display) circuit 916, and further includes a CPU (Central Processing Unit) and the like for performing general operation for controlling receiver 901.
Modular terminal 913 of receiver 901 is connected to a modular terminal of antenna controller 902 through a signal line 993. Receiver 901 supplies power to antenna controller 902 and antenna 903 through signal line 993, and transmits various signals including a signal to switch directivity as appropriate. Upon receiving a reception direction switch signal transmitted from receiver 901, antenna 903 switches its directivity.
Meanwhile, a signal line 992 connects an RF (Radio Frequency) terminal of antenna 903 to an RF terminal of antenna controller 902 and a signal line 991 connects the RF terminal of antenna controller 902 to an RF terminal of tuner 914 so that antenna 903 and receiver 901 are connected to each other through the RF terminals.
Antenna controller 902 supplies power and various signals supplied from receiver 901 to antenna 903 through signal line 992, and receives a broadcast signal from antenna 903 received by the same and transmits the signal to tuner 914.
In receiver 901, the broadcast signal received by a tuner 14 is decoded by a decoder 15, and thereafter it is combined as appropriate with display information such as setting contents or the like in an STB 1 generated in an OSD circuit 16. The resultant signal is output to a not-shown television connected to receiver 901.
As described above, it is considered that connection for power supply and connection for control information are established between the broadcast reception apparatus and the variable directivity antenna. Meanwhile, when the broadcast reception apparatus and the variable directivity antenna are used at home, these apparatuses may be connected by a user. If connection is improper, however, power that should be supplied to the variable directivity antenna is returned to the broadcast reception apparatus, which may result in damage. Therefore, when the broadcast reception apparatus is connected to the variable directivity antenna, the broadcast reception apparatus should be provided with some measure for avoiding such damage.
For example, a polyswitch may be connected to a point of connection to the variable directivity antenna in the broadcast reception apparatus.
Conventionally, it has always been desired that the broadcast reception apparatus is provided with a measure for further ensured safety.